Yes, it would need a large number of glyphs. Not so many as speculated above, though — e.g. we have one glyph that covers communicate, say, tell, hear, speech (all senses), etc. (with some mix-ins for sensory modality); another one that covers give, receive, gift, sell, etc.
Linear languages with European structure need way more words, because the syntax isn't very able to represent the shared concept between these with a single word. We can.
And yes, common structures do get turned into glyphs, or reduced forms.
We also have a barely-explored concept about glyphs being fractal (i.e. if you zoom in, it's actually the shape of an underlying utterance whose syntax "draws" the higher order glyph). This presumably would be a sort of literary or poetic form. (I have composed one very simple example.¹)
Narrative is an utterly different thing in UNLWS. We simply do not have "stories" in the same sense as you're used to. The closest so far is that, rather than the reward/punchline/moral/etc coming from the ordering of things, it comes from understanding the whole, i.e. as an emergent effect of the gestalt.
We don't try to have things that aren't native to 2D. We are, if necessary, able to describe something that happens on a linear timeline - that's pretty easy actually - but it simply isn't the "normal" way to arrange a large utterance. We just aren't all that interested in temporal order. We'd be more likely to represent the underlying structural order, or causality networks.
We do have a quotative, and we've talked about using IPA if we ever needed to literally refer to phonetics for some reason, but so far we simply haven't needed or wanted to do so. (Not for names, either. Names are assigned in a manner that's native to UNLWS; we don't care at all about the phonetic form in another language. Consider ASL, which does this partially [for people who do have sign-names, and under extremely heavy contact with English as a dominant language].)
We never borrow foreign words phonetically. That is just as alien to UNLWS as assigning Chinese hanzi to a name based on their meanings or stroke #s would be to an English-only speaker. We only borrow concepts, and that's only after (sometimes radically) rethinking what those concepts actually are, underlyingly, and what an UNLWS-native perspective of them would entail.
We want to explore two-dimensional language in its own right. Although we do care about expressive power, we really don't care whether it's easily translatable to/from any other languages.
The possiblity of getting ideas out of my head and onto paper without having to linearise everything is very exciting.
Extant natural languages (including dead ones) do not come anywhere close to coming the entire ambit of what could happen in a language.
My interest as a conlanger is precisely that — exploring the boundaries of what language can be, not merely what it is.
As for expressiveness, I think that, within the things we've gotten to, it's just a expressive as English — and actually more so, for the things that are natural to a non-linear or recursive way of thinking.
Obviously we haven't gotten to everything. The lexicon, and grammar, are nowhere near complete. So, yes, we'll need to make lots more to cover everything.
Though also, we deliberately don't make every distinction English does, and we make distinctions English doesn't. It's a very noob move to make a conlang lexically (or even conceptually) 1:1 with a natlang.
It took us several months to figure out a non-linearly-natural way to express "if", for example. A noob would have just chucked in a new glyph and called it a day. We had to rethink fundamentals (like the scoping of irrealis); the result, IMO, is far more interesting.
As for optimality, that has nearly nothing to do with how natlangs spread. You learn a language because you need to — economically, socially, or militarily — not because it's better.
And how they evolve also has almost nothing to do with optimality in any hackery sense. That's an entirely different, stochastic process. It has some tendencies towards eg simplicity, regularity, etc, but just as many against.
In any case, the result is that natural languages don't have teleology; they don't become "better" over time, just different.
I remember reading about the dynamic of language evolution, where an influx of new (and language-wise uneducated) speakers tend to botch and thus simplify much of the existing linguistic constructs. Then there is the opposite effect, where once the group of speakers becomes more uniform and educated, people become more willing to adopt/respect language conventions and even go on looking for ways to express more nuanced distinctions and improve the language in general.
Same thing for euphemisms, insults, etc. And uniformity was far less common before mass media and centralized schooling…
Linguists have a much more descriptivist way of looking at language use and change.
Nuance is not a feature of education; focus is. E.g. AAVE (AKA Ebonics) is currently considered a lower class register, but it has grammatical distinctions that standard English doesn't (like whether an action is part of a pattern, vs a one off).
ETA: also, an influx of non-native speakers tends to result in borrowing of both words and grammar from their native languages. Not just in the development of creoles. What's "correct" is purely defined by consensus; if there are lots of new speakers, that's of course going to shift towards their preferences.
See also: regional / cultural slang, internet / text speak. You can say "n00b" instead of "new person", or ¯\_(ツ)_/¯ instead of "idk" or "I don't know".
Good stuff, nevertheless.